This library function is provided by courtesy of Aaron Lieberman, a former student of 240 in Fall 2020. Student users of the function "clock_speed" report accurate results and reliable performance when called from a C++ function or from an X86 function.
Instructor's comment. Calling clock speed from a C language function presents a challenge. Be prepared to do research (online) to discover how to call this function when the caller is written in C language.
Technologically the language of the caller should not matter at the level of linking bytes together, but in this case it does.